The present invention relates to semiconductor devices and, more specifically, to control devices enabling storage of data in a fusebay arrangement.
In semiconductor chip manufacture, self-testing and -repair systems are often included in a chip design. Such systems typically include a storage device, such as a fusebay, in which repair data may be stored and retrieved by a fusebay controller. The fusebay controller generally processes the repair data during storage and during retrieval, such as by applying compression during storage and decompression during retrieval.
An example of such a system 100 is illustrated in FIG. 1. Repair data for a chip is stored in a fusebay bank 110, typically including primary, secondary, and tertiary fusebays 112, 114, 116, in which arrays of one-time-programmable (OTP) elements or fuses are used to represent the data. A “blown” fuse represents a one, while an intact fuse represents a zero. The repair data in the fusebay bank 110 is typically compressed. Upon startup or power-up of the chip, a repair device 120 loads repair data from the fusebays 112, 114, 116 into corresponding decompressors 122, 124, 126. Data from primary and secondary decompressors 122, 124 is sent to XOR comparator 130, the output of which is sent to XOR comparator 132 for comparison to data from tertiary 126 decompressor. The output of XOR comparator 132 is sent to a repair register 140.
The approach shown in FIG. 1 yields fusebays each dedicated to a single pass of data. In other words, during programming or storage, primary fusebay 112 receives a first pass of data, another fusebay receives the second, and so on. In addition, the sizes of the fusebays are fixed upon construction, so that if a repair pass yields more repair data to store than the number of fuses allocated in its respective fusebay, then there is not enough room for the entire repair pass. These issues arise at least in part because of the manner in which data is stored: a current pass of repair data is simply sent to its respective fusebay, the necessary fuses are blown, and that fusebay becomes a read-only device, containing only the repair data related to the current repair pass.